Liver gene expression response to circadian rhythm disruption
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ABSTRACT: Frequent shift work causes disruption of the circadian rhythm and might on the long-term result in increased health risk. Current biomarkers evaluating the presence of circadian rhythm disturbance (CRD) require 24-hr (around the clock) measurements, which is not practical for use in large-scale (human) studies. The aim of the present study was to identify universal biomarkers for CRD independent of time of day using a transcriptomics approach. Female FVB mice were exposed to six shifts in a clockwise (CW) and counterclockwise (CCW) CRD protocol and sacrificed at baseline and after 1 shift, 6 shifts, 5 days recovery and 14 days recovery, respectively. At six time-points during the day, livers were collected for mRNA microarray analysis. Bioinformatics analysis identified a set of universal markers for CRD. These biomarkers might be useful to measure CRD and can be used later on for monitoring the effectiveness of intervention strategies aiming to prevent or minimize chronic adverse health effects.
Project description:Circadian rhythm disturbances have long been associated with the development of psychiatric disorders, including mood and substance use disorders. Adolescence is a particularly vulnerable time for the onset of psychiatric disorders and for circadian rhythm and sleep disruptions. Preclinical studies have found that circadian rhythm disruption (CRD) impacts the brain and behavior, but this research is largely focused on adult disruptions. Here, we sought to determine the long-term behavioral and neurobiological effects of CRD during early adolescence by exposing mice to 12 h shifts in the light/dark cycle. We hypothesized that adolescent CRD would have a greater effect on psychiatric-related behaviors, relative to adult disruption. To identify possible mechanisms, we also measured gene expression in brain regions relevant to circadian rhythms, mood and reward. We found that disruption during early adolescence, but not adulthood, persistently increased exploratory drive (risk-taking behavior) and cocaine preference when tested later in life. Interestingly, we found sex differences when intravenous cocaine self-administration was tested. While female mice with a history of adolescent CRD had a greater propensity to self-administer cocaine, as well as increased motivation and cue-induced reinstatement, male adolescent CRD mice had reduced motivation and extinction responding. Overall, adolescent CRD in mice caused persistent increases in risky behavior, cocaine reward and cocaine self-administration, which suggests that CRD during adolescence may predispose individuals towards substance use disorders. Importantly, we found that many transcripts were affected by adolescent CRD and these were largely distinct across sex and brain region. Future research is required to elucidate how adolescent CRD affects behaviors relevant to mood- and substance use-related disorders across the 24-hour day, as well as to identify intervention strategies to alleviate disruption during adolescence and novel therapeutic approaches once symptoms have begun.
Project description:To characterize any differences in the effects of Circadian rhythm disorders (CRD) on mice of various ages, we selected young (8-week-old), and aged (18-month-old) mice and created a model of CRD by modifying the light/dark cycle under which they were housed.
Project description:The epidermis is as a highly regenerative barrier protecting organisms from environmental insults, including ultraviolet radiation, the main cause of skin cancer and skin aging. Here we show that time-restricted feeding (RF) shifts the phase and alters the amplitude of the skin circadian clock and affects the expression of approximately 10% of the skin transcriptome. Furthermore, a strikingly large number of skin-expressed genes are acutely regulated by food intake. While the circadian clock is required for daily rhythms in DNA synthesis in epidermal stem cells, RF-induced shifts in clock phase do not alter the phase of DNA synthesis. However, both the expression of the key DNA repair gene Xpa, and the diurnal sensitivity to UVB-induced DNA damage, are altered by RF. Together our findings indicate an unexpected regulation of skin function by time of feeding and emphasize the important link between circadian rhythm, food intake, and skin health.
Project description:This experiment aimed to investigate the effect of different concentrations of ruminal VFAs on the circadian rhythm of gene expression in ORECs of Grain-diet and Hay-diet groups. The ORECs treated with Grain-VFAs and Hay-VFAs were collected at six different timepoints (T0, T4, T8, T12, T16, and T20) for the circadian rhythm analysis using RNA sequencing.
Project description:Circadian rhythms are 24h changes in biochemical, physiological and behavioural processes. When ciricadian rhythm are perturbed, like in shiftwork, lead to negitive health outcomes, such as cancer. We assess circadian transcriptional regulation in healthy (APC+_+) and tumourigenic (APCmin) organoids with (BMAL1_WT) or without (BMAL1_Mut) a functional circadain clock. Our results show that the clock controls several genes involved in stem cell signalling pathways.
Project description:Circadian misalignment, such as in shift work, has been associated with obesity and type 2 diabetes, however, direct effects of circadian misalignment on skeletal muscle insulin sensitivity and muscle molecular circadian clock have never been investigated in humans. Here we investigated insulin sensitivity and muscle metabolism in fourteen healthy young lean men (age 22.4 ± 2.8 years; BMI 22.3 ± 2.1 kg/m2 [mean ± SD]) after a 3-day control protocol and a 3.5-day misalignment protocol induced by a 12-h rapid shift of the behavioral cycle. We show that circadian misalignment results in a significant decrease in peripheral insulin sensitivity due to a reduced skeletal muscle non-oxidative glucose disposal (Rate of disappearance: 23.7 ± 2.4 vs. 18.4 ± 1.4 mg/kg/min; control vs. misalignment; p=0.024). Fasting glucose and FFA levels as well as sleeping metabolic rate were higher during circadian misalignment. Molecular analysis of skeletal muscle biopsies revealed that the molecular circadian clock was not aligned to the new behavourial rhythm, and microarray analysis revealed the human PPAR pathway as a key player in the disturbed energy metabolism upon circadian misallignement. Our findings may provide a mechanism underlying the increased risk of type 2 diabetes among shift workers.
Project description:The duper mutation is a recessive mutation that shortens the period length of the circadian rhythm in Syrian hamsters. These animals show a large phase shift when responding to light pulses. Using two distinct ecotypes and a fast homozygosity mapping strategy, we identified duper as an early nonsense allele of Cryptochrome 1 (Cry1) leading to a short, unstable protein.
Project description:Pathological consequences of circadian misalignment, such as shift work, show considerable individual differences, but the lack of mechanistic understanding hinders precision prevention to prevent and mitigate disease symptoms. Here, we employed an integrative approach involving physiological, transcriptional, and histological phenotypes to examine inter-individual differences in pathological progression during the pre-symptomatic stage, prior to the development of irreversible diseases under chronic circadian misalignment, using wild-type mice exposed to chronic jet-lag (CJL). We observed that CJL markedly increased the prevalence of hepatic steatosis with pronounced inter-individual differences. Stratification of individual mice based on CJL-induced hepatic transcriptomic signature, validated by histopathological analysis, pinpoints dysregulation of lipid metabolism. Moreover, the period and power of intrinsic behavioral rhythms was found to significantly correlate with CJL-induced gene signatures. Together, our results suggest circadian rhythm robustness of the animals contribute to inter-individual variations in pathogenesis of circadian misalignment-induced diseases, and arise the possibility that these physiological indicators may be available for predictive hallmarks of circadian rhythm disorders.
Project description:Molecular analysis of circadian rhythm in mice. Liver tissue of wildtype, Clock mutant and Cry deficient C57BL/6 8- to 10-week-old male mice examined. Keywords = circadian rhythm Keywords: other